package com.omniseckill.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.omniseckill.dto.Result;
import com.omniseckill.entity.VoucherOrder;
import com.omniseckill.mapper.VoucherOrderMapper;
import com.omniseckill.service.ISeckillVoucherService;
import com.omniseckill.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;

import com.omniseckill.utils.RedisIdWorker;
import com.omniseckill.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Slf4j
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {
    @Resource
    private ISeckillVoucherService seckillVoucherService;
    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private RedissonClient redissonClient;

    /*初始化lua脚本*/
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    /*阻塞队列*/
    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);

    /*异步处理线程池*/
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    /*该注解表示在当前类初始化完毕之后去执行*/
    @PostConstruct
    private void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }


    /**
     * 线程任务优化方案：stream消息队列
     */
    private class VoucherOrderHandler implements Runnable {
        String queueName="stream.orders";
        @Override
        public void run() {
            while (true) {
                try {
                    // 1.获取消息队列中的订单信息 XREADGROUP GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS stream.orders >
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queueName, ReadOffset.lastConsumed())
                    );
                    // 2.判断订单信息是否为空
                    if (list == null || list.isEmpty()) {
                        // 如果为null，说明没有消息，继续下一次循环
                        continue;
                    }
                    // 解析数据:消息中的订单信息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> value = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                    // 3.创建订单
                    handleVoucherOrder(voucherOrder);
                    // 4.确认消息 XACK
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                    //处理pending-list异常消息
                    handlePendingList();
                }
            }
        }
        //处理pending-list异常消息
        private void handlePendingList() {
            while(true){
                try {
                    // 1.获取pending-list中的订单信息 XREADGROUP GROUP g1 c1 COUNT 1 STREAMS stream.orders 0
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(queueName, ReadOffset.from("0"))
                    );
                    // 2.判断订单信息是否为空
                    if (list == null || list.isEmpty()) {
                        // 如果为null，说明pending-list没有异常消息，结束循环
                        break;
                    }
                    // 解析数据
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> value = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                    // 3.创建订单
                    handleVoucherOrder(voucherOrder);
                    // 4.确认消息 XACK
                    stringRedisTemplate.opsForStream().acknowledge("s1", "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理pending-list订单异常", e);
                    try{
                        Thread.sleep(20);
                    } catch (InterruptedException ex) {
                        throw new RuntimeException(ex);
                    }
                }
            }
        }
    }

    /**
     * 线程任务原始方案：阻塞队列
     */
    //线程任务：初始化完毕后，就会去队列中拿信息
    /*
    private class VoucherOrderHandler implements Runnable {

        @Override
        public void run() {
            while (true) {
                try {
                    //1.获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    //2.创建订单
                    handleVoucherOrder(voucherOrder);
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                }
            }
        }
    }*/



    /**
     * 异步处理操作：创建订单
     * @param voucherOrder
     */
    @Transactional
    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        //1.获取用户
        Long userId = voucherOrder.getUserId();
        //2.创建锁对象
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        //3.尝试获取锁
        boolean isLock = lock.tryLock();
        //4.判断是否获取锁成功
        if (!isLock) {
            //获取锁失败，直接返回失败或者重试
            log.error("不允许重复下单！");
            return;
        }
        try {
            //注意：由于spring的事务是放在threadLocal中，此时的是多线程，事务会失效
            proxy.createVoucherOrder(voucherOrder);
        } finally {
            //释放锁
            lock.unlock();
        }
    }

    /**
     * 创建订单
     * @param voucherOrder
     */
    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        //5.一人一单逻辑
        //用户id
//        Long userId = UserHolder.getUser().getId();
        Long userId=voucherOrder.getUserId();

        //5.1查询订单
        int count = query()
                .eq("user_id", userId)
                .eq("voucher_id", voucherOrder.getVoucherId())
                .count();
        //5.2判断是否存在
        if (count > 0){
            //用户已经购买过了
            log.error("用户已经购买过一次！");
            return;
        }
        //6.扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock=stock-1") //set stock = stock -1
                .eq("voucher_id", voucherOrder.getVoucherId())
                .gt("stock", 0).update();//where id = ？ and stock > 0
        if (!success){
            //扣减失败
            log.error("库存不足！");
            return;
        }
        //7.创建订单
//        VoucherOrder voucherOrder = new VoucherOrder();
//        //7.1订单id
//        long orderId = redisIdWorker.nextId("order");
//        voucherOrder.setId(orderId);
//        //7.2用户id
//        voucherOrder.setUserId(userId);
//        //7.3代金券id
//        voucherOrder.setVoucherId(voucherOrder);

        save(voucherOrder);

        //8.返回订单id
//        return Result.ok(orderId);
    }



    //初始化代理对象
    private IVoucherOrderService proxy;

    /**
     * 异步秒杀：stream消息队列实现
     * @param voucherId
     * @return
     */
    @Override
    public Result seckillVoucher(Long voucherId) {
        //获取用户
        Long userId = UserHolder.getUser().getId();
        //获取订单
        long orderId = redisIdWorker.nextId("order");
        //1.执行 Lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString(),String.valueOf(orderId)
        );
        //2.判断结果是否为0
        int r = result.intValue();
        if (r != 0){
            //2.1 不为 0，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不可重复下单");
        }
        //3.获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        //4.返回订单id
        return Result.ok(orderId);
    }

    /**
     * 秒杀优化方案：阻塞队列，开启新线程
     */
    /*
    @Override
    public Result seckillVoucher(Long voucherId) {
        //获取用户
        Long userId = UserHolder.getUser().getId();
//        long orderId=redisIdWorker.nextId("order");
        //1.执行 Lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString()
//                ,String.valueOf(orderId)
        );
        //2.判断结果是否为0
        int r = result.intValue();
        if (r != 0){
            //2.1 不为 0，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不可重复下单");
        }
        //2.2 为 0，有购买资格，把下单信息保存到阻塞队列
        //TODO 保存阻塞队列
        VoucherOrder voucherOrder = new VoucherOrder();
        //2.3 订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        //2.4 用户id
        voucherOrder.setUserId(userId);
        //2.5 代金券id
        voucherOrder.setVoucherId(voucherId);
        //2.6 放入阻塞队列
        orderTasks.add(voucherOrder);

        //3.获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        //4.返回订单id
        return Result.ok(orderId);
    }*/

    /**
     * 秒杀原始方案：分布式锁
     */
    /*
    @Override
    public Result seckillVoucher(Long voucherId) {
        //1.查询优惠券
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        //2.判断秒杀是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())){
            //尚未开始
            return Result.fail("秒杀尚未开始！");
        }
        //3.判断秒杀是否已经结束
        if (voucher.getEndTime().isBefore(LocalDateTime.now())){
            //已经结束
            return Result.fail("秒杀已经结束！");
        }
        //4.判断库存是否充足
        if (voucher.getStock() < 1){
            //库存不足
            return Result.fail("库存不足！");
        }

        //用户id
        Long userId = UserHolder.getUser().getId();
        //创建锁对象(分布式锁)
//        SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);//这个代码不用了，因为我们现在要使用分布式锁
        RLock lock = redissonClient.getLock("lock:order:" + userId);

        //获取锁对象
//        boolean isLock = lock.tryLock(1200);
        boolean isLock = lock.tryLock();

        //加锁失败
        if (!isLock) {
            return Result.fail("不允许重复下单");
        }
        try {
            //获取代理对象(事务)
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVoucherOrder(voucherId);
        } finally {
            //释放锁
            lock.unlock();
        }

//       //锁定当前用户（同步锁）
//        synchronized (userId.toString().intern()) {
//       //获取代理对象（事务）
//        IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
//        return proxy.createVoucherOrder(voucherId);
//        }
    }*/


}
